This invention relates to a valve reactor for high-voltage direct-current (HVDC) transmission systems.
HVDC transmission systems are currently in general use in the distribution of electrical energy, as the connecting elements between two three-phase alternating-current power networks. Line-actuated controlled semiconductors, such as thyristors, convert the three-phase current to HVDC for transmission at the transmitting end and back into three-phase current at the receiving end. The highest attainable thyristor operating voltage is small in comparison with the valve voltage required for economical transmission. For this reason, a HVDC transmission valve must be made up of a number of thyristors connected in series. In order to limit the rate of current rise in a distributed manner, each of the individual thyristors in a HVDC transmission valve must additionally be connected in series with a valve reactor or choke having a choke winding and a liquid-cooled choke core.